The link between interleukin-6, anti-cyclic citrullinated peptide and highly sensitive C-reactive protein in type 2 diabetes: age-effect study

Anti-cyclic citrullinated peptide (ACCP) autoantibodies are likely to be involved in the development of rheumatoid arthritis in at least 70 % of the patients. These autoantibodies are associated with type 1 diabetes and may predict the development of rheumatoid arthritis in later life. This study aimed to examine the association between interleukin-6 (IL-6), a proinflammatory cytokine, highly sensitive C-reactive protein (hsCRP), and ACCP autoantibodies in type 2 diabetes (T2D) patients without past or current history of arthropathy taking in consideration the age-effect factor. A total number of 70 T2D patients and 60 healthy subjects were recruited from the center of diabetes in Erbil, Iraq. The patients were grouped into two: group I (age 35–45 years): group IA, healthy subjects and group IB, diabetic patients; group II (age ≥60 years): group IIA, healthy subjects and group IIB, diabetic patients. Fasting serum glucose, HbA_1c%, lipid profile, IL-6, hsCRP, and ACCP autoantibodies were determined. Significant alterations in lipid profile were observed in group IIB compared with group IB. Patients of group IIB have significant high serum IL-6 (458.3 ± 43.04 pg/ml), hsCRP (5.576 ± 0.643 mg/L), and ACCP autoantibodies (74.31 ± 8 U/ml) than corresponding group IB: IL-6 (381.4 ± 22.6 pg/ml), hsCRP (4.92 ± 0.343 mg/L), and ACCP (49.43 ± 7.09 U/ml). Significant positive correlation (r = 0.445) between serum IL-6 and ACCP autoantibodies was observed only in group IB. It concludes that proinflammatory markers and autoantibodies that related to arthritis are increased in old diabetic patients compared with younger age, and IL-6 correlated with ACCP autoantibodies in younger patients which indicated age effect.